Once a person is appointed and received as an Ambassador, very few incidents can happen that would dislodge the person from the post. Even if the whole diaspora literally detests the ambassador, or the ambassador commits some gross transgression, the person remains an Ambassador.

However, if the sending country recalls their ambassador, then the person’s tour of duty is effectively ended. The recalling of one’s own ambassador signals a country’s displeasure at the other country, not at the ambassador. This has to be differentiated from a normal Letter of Recall when a new ambassador is appointed.

Another more common way is when the host country declares the ambassador persona non grata – quite literally ‘no longer welcome’. This is usually accompanied by a set time limit for the ambassador (and sometimes family) to leave the country. In most cases, a grace period of 48 hours is given between the official notification and the deadline for leaving. As can be expected, this signals the host country’s displeasure. No reason for this declaration has to be given, or is even expected. This was the case when Serbia declared Malaysia’s ambassador in Belgrade as persona non grata.

The most common way for an ambassador to no longer be an Ambassador is when the appointment of a new Ambassador takes place. The new Ambassador normally brings with him / her the Letter of Recall of the previous ambassador, signalling that the predecessor no longer has the right to all the immunities and privileges accorded a serving Ambassador.

Just as a footnote: A ‘High Commissioner’ is just an Ambassador by another name. It is a title given to ambassadors when the sending state and the receiving state are both members of the British Commonwealth. In diplomatic practice, there is no difference between a High Commissioner and an Ambassador.